title: Microleakage of the prosthetic abutment/implant interface with internal and external connection: in vitro study.
abstract: OBJECTIVE
  This study determined the degree of marginal microleakage of the abutment-implant interface on platforms with Morse taper connection and external connection.
  
  
  METHODS
  For this in vitro study, 42 implants, 21 with external connection and 21 with Morse taper connection, were used, immersed in acrylic resin cylinders. Each implant was joined by a prosthetic abutment screw tightened at different degrees, forming the six study groups: (1) External connection, manual tightening (2) External connection, 20 Newton (N) tightening (3) External connection, 30 N tightening (4) Morse taper connection, manual tightening (5) Morse taper connection, 20 N tightening (6) orse taper connection, 30 N tightening. All samples were subjected to load cycling and thermocycling. Then, they were submerged in a solution of 0.2% methylene blue for 24 h. Finally, the microleakage was measured via 20× optical microscopy in each study group, average was obtained, and Mann-Whitney test was applied.
  
  
  RESULTS
  Statistically significant differences (P < 0.001) were found between the levels of microleakage presented in the Morse taper connection implants (1.48) and external connection implants (2.8) in all three types of tightening. Microleakage levels decreases when increasing torque is applied to the screws.
  
  
  CONCLUSIONS
  Morse taper connection implants showed lower levels of microleakage than external connection implants; also, it was observed that microleakage decreases in the way torque increases.
authors.affiliation: Postgrado de Rehabilitación Oral, Universidad de Talca, Talca, Chile.
authors.forename: Carlos
authors.initials: C
authors.lastname: Larrucea Verdugo
authors.forename: Guido
authors.initials: G
authors.lastname: Jaramillo Núñez
authors.forename: Ariel
authors.initials: A
authors.lastname: Acevedo Avila
authors.forename: Carlo
authors.initials: C
authors.lastname: Larrucea San Martín
mesh_terms: D000044:Dental Abutments; D015921:Dental Implants; D003763:Dental Leakage; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D066298:In Vitro Techniques; D013499:Surface Properties
chemical_list: D015921:Dental Implants
keywords: external connection; implants; internal connection; microfiltration; torque